Photopatch Test Study (POST Study)

Plain-language summary

In the year 2000, a group of specialists with an interest in contact dermatitis and photobiology/photophysics set up a taskforce under the umbrella of the European Society for Contact Dermatitis and the European Society for Photodermatology. This came about as a result of an awareness, that photopatch testing was under-used, there were inconsistencies in methodology and scoring of results, and there was a lack of up-to-date choice of test photoallergens. A consensus on the methodology of photopatch testing arose from this, although some inconsistencies on the methodology could not be solved and variations on the technique were accepted. Since then a European multicentre photopatch test study (EMCPPTS) was conducted in 30 clinics from 2008-2011. The EMCPPTS test agents comprised 19 UV absorbers, and 5 topical non-steroidal anti-inflammatory drugs available in Europe. More than 1,000 patients took part in this study that showed that ketoprofen and related chemicals and classical UV-filters were the main photoallergens. Since then the taskforce have met again (2012) and on the basis of the results of the ECMPPTS, on previous publications reporting cases of photoallergic contact dermatitis, and on the presence or absence of these agents in consumer products within the European market or other accessible markets, 20 substances were chosen to form the baseline European photopatch test series. Fifteen additional substances were chosen to be included in the extended photopatch test series which may be used as an additional screen alongside patients' own product. Twenty-six other agents that are no longer produced or are no longer used in the European markets have been considered to be no longer relevant for regular photopatch testing and were removed. It was suggested from this taskforce that the study should be repeated in approximately five years, as it is expected that new photoallergens will continue to emerge despite pre-marketing screening measures. Therefore members of this taskforce subsequently met in 2015, to discuss the aim of performing a very similar study, commencing in 2016. However, the investigators aim to focus specifically on methodology as in all previous studies a variety of methods of photopatch testing have been utilised. The investigators therefore aim to improve standardisation of this test. This agreed methodology will therefore enable better comparative studies in the future and hopefully encourage greater numbers of would-be users of this form of patch testing, as due to a previous level of uncertainty, many general dermatologists have been discouraged from using this technique.

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Trial details